Fixed null parameter warning in Mage_Catalog_Model_Layer_Filter_Attribute

[fballiano]

Fixes #3925

[ioweb-gr]

Nope it didn't work for me for a URL of the type

/mobile-phones?core_count=41&gdiktia=168&nfcsosto=376&ram=50%2C54

or
/mobile-phones?core_count=41&gdiktia=168&nfcsosto=376&ram=50,54

[ioweb-gr]

That's because _getOptionText returns false and the operator doesn't affect it

[ioweb-gr]

How about this ? It should cover null and false and empty values

        $text = $this->_getOptionText($filter);
        if ($filter && !empty($text)) {
            $this->_getResource()->applyFilterToCollection($this, $filter);
            $this->getLayer()->getState()->addFilter($this->_createItem($text, $filter));
            $this->_items = [];
        }

[fballiano]

right, can you check this new version?

it seems to me that $text really needs to be a string for:
$this->getLayer()->getState()->addFilter($this->_createItem($text, $filter));
to work

[ioweb-gr]

That also works

[fballiano]

if you confirm me that it works I'll merge it right away and release a 20.6

[ioweb-gr]

Yeah I already checked it, it didn't throw the error.

[fballiano]

let's consider this as a review and merge it